1. Field of Invention
Our invention relates generally to steps for cargo transport vehicles, and more particularly to a step-type platform that is releasably placeable to aid access through the side door of such a vehicle and when not in use is stored on the vehicle.
2. Background and Description of the Prior Art
The highway transport of various cargo is carried out in trucks or trailers having a peripherally defined box-like containment space carried on a ladder-type frame with one or more depending wheel trucks to aid locomotion. Such vehicles, whether trucks and trailers, generally have doors in their rear end portions for access for loading and unloading. The configuration and dimensioning of such trucks and trailers has become reasonably standardized so that loading facilities may be constructed to accommodate almost any of such vehicles to effectuate loading and unloading operations through the rear doors.
Many such vehicles of the modern day, however, are also provided with side access doors. This is especially true in vehicles intended for short distance hauls such as for local deliveries of goods and vehicles that are subdivided into two or more separated chambers for containment of particular goods, especially such goods as must be maintained under different environmental conditions. These latter vehicles must generally be both loaded and unloaded through side doors. Since most trucks and trailers are generally formed with a ladder-type frame that supports a cargo containment body and that containment body is maintained at a distance of approximately four feet above a supporting surface to provide for proper locomotion, access to such side doors has heretofore presented problems. Our invention seeks to solve these problems.
Though most loading docks have decks of substantially the proper height for ingress and egress to the side doors of a trailer, since those doors are usually of the same height as rear doors, nonetheless those dock facilities are generally designed for trailer positioning with the rear of a vehicle adjacent the dock for access to the rear doors. Commonly neither a trailer nor truck can be appropriately positioned relative to such dock structures to allow access to side doors, or at least to conveniently do so. Additionally in local delivery work, and generally in work with cargo containment spaces that are subdivided, access must often be had in locations where there are no dock structures. This problem of side door access is exacerbated when the space being accessed through the side door is a freezer compartment, as in this case any structures adjacent the door often become cold to condense atmospheric moisture and freeze it to ice which slickens adjacent surfaces and makes access thereover hazardous to workers.
In the past where problems of such side door access have been recognized and dealt with at all, generally vertically oriented ladder-like step structures have been provided depending from a truck frame vertically below or adjacently below a side door. These ladder-like devices, however, have not proven particularly satisfactory for access as they provide support for a worker's foot only spacedly below the door opening and not at the level of a door threshold. Such step structures also generally have been of limited width to aid access only at a particular portion of the door opening or adjacent to it, which often is not appropriate to aid loading or unloading of merchandise through a door. The vertical extent of such step structures is also limited as they generally have been fastened to a vehicle in a rigid immovable fashion and by reason of this, the step structure cannot depend downwardly too closely to a surface supporting the vehicle or the step structure may come into contact with irregularities in a supporting surface to cause damage to the step structure or possibly even to a vehicle.
Our invention resolves this problem by providing a releasably positionable step structure that has a horizontal surface of substantial areal extent at the level of and immediately adjacent a threshold of a vehicle side door. The step structure provides a planar step with perpendicularly depending spaced legs releasably carried in vertically oriented channels defined in fastening brackets supported by the vehicle frame below the cargo containment member defining a side door to be serviced. The step is releasably maintained in operative mode by pin-type fasteners extending through appropriately positioned holes defined in associated fastening brackets and step legs.
The problems of frozen surfaces on such a step that is associated with a refrigerated cargo compartment is alleviated by providing a horizontal step surface formed of expanded metal firstly, to provide a roughened surface with projections and orifices that tend to prevent slipping and secondly, to provide a surface that does not uniformly or well transmit heat so that freezing is lessened in general and if there be any freezing, it occurs in discrete spaced areas of the stepped surface rather than uniformly over the entire step surface.
With a step such as ours, it is necessary that it project laterally outwardly from the side of the trailer to properly serve its purpose of supporting a user during ingress and egress for loading and unload. Such a step structure would necessarily cause operative problems for a trailer being serviced if it were to remain in operative position during vehicle transport. By reason of this, our step must be releasably positionable so that it may be removed during periods of non-use. Our mounting system provides simple and easy means for step removal and also for positional maintenance of a step in a storage mode during periods of non-use.
To accomplish step storage, we provide a fastening system with fastening brackets, carried on the side of the trailer frame, that have channels defined vertically through the brackets. A step may be stored in such brackets by turning it with its fastening legs extending upwardly and its horizontal step portion extending inwardly under the vehicle frame, moving the legs upwardly into the support brackets from below, and inserting releasable fastening pins in cooperating holes defined in both brackets and step legs to extend between the elements in a releasable fastening relationship. The step is thusly stored in a convenient, out of the way position during periods of non-use, but it remains readily available whenever desired.
In some vehicles a wheel truck structure may be located immediately beneath a side door defined in the cargo containment chamber to prevent storage of our step in the same brackets which support it in its operative mode outwardly adjacent a side door. If this construction be present, a second set of fastening brackets may be established spaced forwardly or rearwardly from the side door for step storage in a position where it will not interfere with any wheel truck structures of the vehicle. In some vehicles, two or more spacedly separated side doors are defined and in this instance, one step structure might conveniently be used with all such side doors. Ordinarily if there be multiple side doors, at least one such door will be in a position where the step structure may be stored in the normal fastening brackets associated with that particular door.
It is to be noted that our step may serve an additional function of maintaining a side door of a trailer or truck in open condition when the step is operatively positioned in its use mode. Normally a side door of a cartage vehicle extends somewhat below the upper surface of the threshold of the door opening closed thereby. By reason of this, when our step structure is operatively positioned at an elevation substantially the same as the door threshold, the door associated with that door opening may not be moved over our step structure. The door will have to be open before the step structure can be operatively placed and the step structure will thereafter prevent the door from closing accidentally during use of our step, to aid in preventing damage to the door structure itself or to a workman by reason of accidental closure.
Our invention resides not in any one of the foregoing features per se , but rather in the synergistic combination of all of its structures that combine to provide the functions necessarily flowing therefrom.